mm: memory: check userfaultfd_wp() in vmf_orig_pte_uffd_wp()
Add userfaultfd_wp() check in vmf_orig_pte_uffd_wp() to avoid the
unnecessary FAULT_FLAG_ORIG_PTE_VALID check/pte_marker_entry_uffd_wp() in
most pagefault, note, the function vmf_orig_pte_uffd_wp() is not inlined
in the two kernel versions, the difference is shown below,
perf date,
perf report -i perf.data.before | grep vmf
0.17% 0.13% lat_pagefault [kernel.kallsyms] [k] vmf_orig_pte_uffd_wp.part.0.isra.0
perf report -i perf.data.after | grep vmf
lat_pagefault -W 5 -N 5 /tmp/XXX
latency before after diff
average(8 tests) 0.262675 0.
2600375 -0.
0026375
Although it's a small, but the uffd_wp is a new feature than previous
kernel, when the vma is not registered with UFFD_WP, let's avoid to
execute the new logical, also adding __always_inline attribute to
vmf_orig_pte_uffd_wp(), which make set_pte_range() only check VM_UFFD_WP
flags without the function call. In addition, directly call the
vmf_orig_pte_uffd_wp() in do_anonymous_page() and set_pte_range() to save
an uffd_wp variable.
Link: https://lkml.kernel.org/r/20240422030039.3293568-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>